Retirement Benefits (Tables)

12 Months Ended

Dec. 31, 2018

Defined Benefit Plan and Other Postretirement Benefit Plans Table Text Block [Line Items]

Schedule of Changes in Projected Benefit Obligations

The following tables summarize the Company’s change in benefit obligation, change in plan assets and amounts recognized in the Statements of Financial Position for the years ended December 31, 2018 and 2017:

Puget Energy and Puget Sound Energy	Qualified Pension Benefits						SERP Pension Benefits						Other Benefits
(Dollars in Thousands)	2018			2017			2018			2017			2018			2017
Change in benefit obligation:
Benefit obligation at beginning of period	$	700,481		$	652,607		$	55,754		$	51,734		$	11,454		$	11,194
Amendments	—			—			1,446			—			—			—
Service cost	22,757			20,081			847			913			69			72
Interest cost	27,303			28,373			2,120			2,285			444			500
Actuarial loss (gain)	(29,067		)	40,945			1,122			2,722			(379		)	725
Benefits paid	(42,662		)	(40,594		)	(5,581		)	(1,900		)	(1,037		)	(1,137		)
Medicare part D subsidy received	—			—			—			—			85			100
Administrative expense	(1,169		)	(931		)	—			—			—			—
Benefit obligation at end of period	$	677,643		$	700,481		$	55,708		$	55,754		$	10,636		$	11,454

Schedule of Changes in Fair Value of Plan Assets

Puget Energy and Puget Sound Energy	Qualified Pension Benefits						SERP Pension Benefits						Other Benefits
(Dollars in Thousands)	2018			2017			2018			2017			2018			2017
Change in plan assets:
Fair value of plan assets at beginning of period	$	704,360		$	620,260		$	—		$	—		$	7,138		$	7,200
Actual return on plan assets	(38,379		)	107,836			—			—			(395		)	784
Employer contribution	18,000			18,000			5,581			1,900			254			291
Benefits paid	(42,662		)	(40,594		)	(5,581		)	(1,900		)	(1,037		)	(1,137		)
Administrative expense	(1,077		)	(1,142		)	—			—			—			—
Fair value of plan assets at end of period	$	640,242		$	704,360		$	—		$	—		$	5,960		$	7,138
Funded status at end of period	$	(37,401	)	$	3,879		$	(55,708	)	$	(55,754	)	$	(4,676	)	$	(4,316	)

Schedule of Amounts Recognized in Balance Sheet and Accumulated Other Comprehensive Income

Puget Energy and Puget Sound Energy	Qualified Pension Benefits					SERP Pension Benefits						Other Benefits
(Dollars in Thousands)	2018			2017		2018			2017			2018			2017
Amounts recognized in Statement of Financial Position consist of:
Noncurrent assets	$	—		$	3,879	$	—		$	—		$	—		$	—
Current liabilities	—			—		(6,249		)	(5,486		)	(332		)	(317		)
Noncurrent liabilities	(37,401		)	—		(49,459		)	(50,268		)	(4,344		)	(3,999		)
Net assets (liabilities)	$	(37,401	)	$	3,879	$	(55,708	)	$	(55,754	)	$	(4,676	)	$	(4,316	)

Schedule of Accumulated Benefit Obligations in Excess of Fair Value of Plan Assets [Table Text Block]

Puget Energy and Puget Sound Energy	Qualified Pension Benefits				SERP Pension Benefits				Other Benefits
(Dollars in Thousands)	2018		2017		2018		2017		2018		2017
Pension Plans with an Accumulated Benefit Obligation in excess of Plan Assets:
Projected benefit obligation	$	677,643	$	700,481	$	55,708	$	55,754	$	10,636	$	11,454
Accumulated benefit obligation	668,469		688,908		51,031		52,681		10,557		11,367
Fair value of plan assets	640,242		704,360		—		—		5,960		7,138

Schedule of Net Benefit Costs

The following tables summarize Puget Energy's and PSE's net periodic benefit cost for the years ended December 31, 2018, 2017 and 2016:

Puget Energy	Qualified Pension Benefits									SERP Pension Benefits						Other Benefits
(Dollars in Thousands)	2018			2017			2016			2018		2017		2016		2018			2017			2016
Components of net periodic benefit cost:
Service cost	$	22,757		$	20,081		$	18,913		$	847	$	913	$	1,085	$	69		$	72		$	93
Interest cost	27,303			28,373			28,689			2,120		2,285		2,325		444			500			533
Expected return on plan assets	(50,202		)	(47,784		)	(46,619		)	—		—		—		(472		)	(461		)	(446		)
Amortization of prior service cost (credit)	(1,980		)	(1,980		)	(1,980		)	1,580		42		42		—			—			—
Amortization of net loss (gain)	2,187			—			—			42		1,077		911		(335		)	(402		)	(386		)
Net periodic benefit cost	$	65		$	(1,310	)	$	(997	)	$	4,589	$	4,317	$	4,363	$	(294	)	$	(291	)	$	(206	)

Schedule of Amounts Recognized in Other Comprehensive Income (Loss)

The following tables summarize Puget Energy's and PSE's benefit obligations recognized in other comprehensive income (OCI) for the years ended December 31, 2018 and 2017:

Puget Energy	Qualified Pension Benefits						SERP Pension Benefits						Other Benefits
(Dollars in Thousands)	2018			2017			2018			2017			2018		2017
Other changes (pre-tax) in plan assets and benefit obligations recognized in other comprehensive income:
Net loss (gain)	$	59,422		$	(18,896	)	$	1,122		$	2,722		$	488	$	403
Amortization of net (loss) gain	(2,187		)	—			(1,580		)	(1,076		)	335		401
Settlements, mergers, sales, and closures	—			—			(619		)	—			—		—
Prior service cost (credit)	—			—			1,446			—			—		—
Amortization of prior service (cost) credit	1,980			1,980			(42		)	(42		)	—		—
Total change in other comprehensive income for year	$	59,215		$	(16,916	)	$	327		$	1,604		$	823	$	804

Schedule of Assumptions Used

In accounting for pension and other benefit obligations and costs under the plans, the following weighted-average actuarial assumptions were used by the Company:

	Qualified Pension Benefits						SERP Pension Benefits						Other Benefits
Benefit Obligation Assumptions	2018		2017		2016		2018		2017		2016		2018		2017		2016
Discount rate	4.40	%	4.00	%	4.50	%	4.40	%	4.00	%	4.50	%	4.40	%	4.00	%	4.50	%
Rate of compensation increase	4.50		4.50		4.50		4.50		4.50		4.50		4.50		4.50		4.50
Medical trend rate	—		—		—		—		—		—		7.60		6.80		8.80
Benefit Cost Assumptions
Discount rate	4.40	%	4.50	%	4.65	%	4.40	%	4.50	%	4.65	%	4.40	%	4.50	%	4.65	%
Return on plan assets	7.50		7.45		7.75		—		—		—		7.00		6.75		6.75
Rate of compensation increase	4.50		4.50		4.50		4.50		4.50		4.50		4.50		4.50		4.50
Medical trend rate	—		—		—		—		—		—		7.60		9.50		5.30

Schedule of Effect of One-Percentage-Point Change in Assumed Health Care Cost Trend Rates

The assumed medical inflation rate used to determine benefit obligations is 7.60% in 2019 grading down to 3.90% in 2020.  A 1.0% change in the assumed medical inflation rate would have the following effects:

	2018					2017
(Dollars in Thousands)	1% Increase		1% Decrease			1% Increase		1% Decrease
Effect on post-retirement benefit obligation	$	19	$	(18	)	$	23	$	(22	)
Effect on service and interest cost components	1		(1		)	1		(1		)

Schedule of Expected Benefit Payments

The expected total benefits to be paid during the next five years and the aggregate total to be paid for the five years thereafter are as follows:

(Dollars in Thousands)	2019		2020		2021		2022		2023		2024-2027
Qualified Pension total benefits	$	43,700	$	45,100	$	45,900	$	47,100	$	48,500	$	252,400
SERP Pension total benefits	6,249		4,993		1,887		5,378		3,678		39,400
Other Benefits total with Medicare Part D subsidy	1,112		1,094		1,064		1,038		1,008		4,410
Other Benefits total without Medicare Part D subsidy	892		863		899		872		841		3,704

Schedule of Allocation of Plan Assets

The following table sets forth by level, within the fair value hierarchy, the qualified pension plan as of December 31, 2018 and 2017:

	Recurring Fair Value Measures						Recurring Fair Value Measures
	As of December 31, 2018						As of December 31, 2017
(Dollars in Thousands)	Level 1		Level 2		Total		Level 1		Level 2		Total
Assets:
Mutual Funds	$	103,661	$	—	$	103,661	$	117,796	$	—	$	117,796
Common Stock	177,949		—		177,949		209,504		—		209,504
Government Securities	—		—		—		18,316		23,782		42,098
Corporate Bonds	—		—		—		—		34,588		34,588
Cash and cash equivalents	—		702		702		2,684		9,304		11,988
Subtotal	$	281,610	$	702	282,312		$	348,300	$	67,674	415,974
Investments measured at NAV1					356,586						237,427
Net (payable) receivable					1,345						50,959
Total assets					$	640,243					$	704,360

_______________

¹  In accordance with ASU 2015-07, "Fair Value Measurement (Topic 820): Disclosures for Investments in Certain Entities that Calculate Net Asset Value per Share (or Its Equivalent)", certain investments that were measured at NAV per share (or its equivalent) have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the line items presented in the statement of net assets available for benefits. Investments measured at NAV primarily consist of common/collective trust funds and two partnerships held as of December 31, 2018.

Mesirow Institutional Multi-Strategy Fund Partnership, L.P. utilizes a combination of long and short strategies through investments in investment funds. The major strategy allocations of the investment funds include (1) Investments in debt obligations of public and private entities; typically, in financial duress, and (2) Investments in equity positions on a global basis utilizing fundamental analysis.

Grosvenor Institutional Partners Fund, L.P invests substantially all of the fund assets available in the Grosvenor Master Fund, a Cayman Islands exempted company which is sponsored, managed and has the same investment objective as the Partnership fund. In addition to the Master Fund, investments are made primarily in offshore investment funds, investment partnerships, and pooled investment vehicles; collectively referred to as Portfolio Funds, which generally implement "nontraditional" or "alternative" investment strategies.

To obtain the desired return needed to fund the pension benefit plans, the Retirement Plan Committee has established investment allocation percentages by asset classes as follows:

	Allocation
Asset Class	Minimum		Target		Maximum
Domestic large cap equity	25	%	31	%	40	%
Domestic small cap equity	—		9		15
Non-U.S. equity	10		25		30
Fixed income	15		25		30
Real estate	—		—		10
Absolute return	5		10		15
Cash	—		—		5

The following table sets forth by level, within the fair value hierarchy, the Other Benefits plan assets which consist of insurance benefits for retired employees, at fair value:

	Recurring Fair Value Measures						Recurring Fair Value Measures
	As of December 31, 2018						As of December 31, 2017
(Dollars in Thousands)	Level 1		Level 2		Total		Level 1		Level 2		Total
Assets:
Mutual fund1	$	5,910	$	—	$	5,910	$	7,089	$	—	$	7,089
Investments measured at NAV2					50						49
Total assets					$	5,960					$	7,138

_______________

¹  This is a publicly traded balanced mutual fund.  The fund seeks regular income, conservation of principal, and an opportunity for long-term growth of principal and income.  The fair value is determined by taking the number of shares owned by the plan, and multiplying by the market price as of December 31, 2018.

²  In accordance with ASU 2015-07, "Fair Value Measurement (Topic 820): Disclosures for Investments in Certain Entities that Calculate Net Asset Value per Share (or Its Equivalent)", certain investments that were measured at NAV per share (or its equivalent) have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the line items presented in the statement of net assets available for benefits. Investments measured at NAV consist of a common/collective trust fund as of December 31, 2018.

Parent Company [Member]

Defined Benefit Plan and Other Postretirement Benefit Plans Table Text Block [Line Items]

Schedule of Amounts Recognized in Balance Sheet and Accumulated Other Comprehensive Income

The following tables summarize Puget Energy's and PSE's pension benefit amounts recognized in AOCI for the years ended December 31, 2018 and 2017:

Puget Energy	Qualified Pension Benefits						SERP Pension Benefits				Other Benefits
(Dollars in Thousands)	2018			2017			2018		2017		2018			2017
Amounts recognized in Accumulated Other Comprehensive Income consist of:
Net loss (gain)	$	94,929		$	37,693		$	9,612	$	10,689	$	(2,564	)	$	(3,386	)
Prior service cost (credit)	(5,863		)	(7,843		)	1,607		204		—			—
Total	$	89,066		$	29,850		$	11,219	$	10,893	$	(2,564	)	$	(3,386	)

Subsidiaries [Member]

Defined Benefit Plan and Other Postretirement Benefit Plans Table Text Block [Line Items]

Schedule of Amounts Recognized in Balance Sheet and Accumulated Other Comprehensive Income

Puget Sound Energy	Qualified Pension Benefits						SERP Pension Benefits				Other Benefits
(Dollars in Thousands)	2018			2017			2018		2017		2018			2017
Amounts recognized in Accumulated Other Comprehensive Income consist of:
Net loss (gain)	$	229,819		$	185,277		$	11,450	$	13,134	$	(3,857	)	$	(4,901	)
Prior service cost (credit)	(4,659		)	(6,232		)	1,609		208		—			—
Total	$	225,160		$	179,045		$	13,059	$	13,342	$	(3,857	)	$	(4,901	)

Schedule of Net Benefit Costs

Puget Sound Energy	Qualified Pension Benefits									SERP Pension Benefits						Other Benefits
(Dollars in Thousands)	2018			2017			2016			2018		2017		2016		2018			2017			2016
Components of net periodic benefit cost:
Service cost	$	22,757		$	20,081		$	18,913		$	847	$	913	$	1,085	$	69		$	72		$	93
Interest cost	27,303			28,373			28,689			2,120		2,285		2,325		444			500			533
Expected return on plan assets	(50,240		)	(47,862		)	(46,814		)	—		—		—		(472		)	(461		)	(446		)
Amortization of prior service cost (credit)	(1,573		)	(1,573		)	(1,573		)	44		44		44		—			—			—
Amortization of net loss (gain)	14,917			13,048			15,257			2,069		1,565		1,330		(556		)	(641		)	(632		)
Net periodic benefit cost	$	13,164		$	12,067		$	14,472		$	5,080	$	4,807	$	4,784	$	(515	)	$	(530	)	$	(452	)

Schedule of Amounts Recognized in Other Comprehensive Income (Loss)

Puget Sound Energy	Qualified Pension Benefit						SERP Pension Benefits						Other Benefits
(Dollars in Thousands)	2018			2017			2018			2017			2018		2017
Other changes (pre-tax) in plan assets and benefit obligations recognized in other comprehensive income:
Net loss (gain)	$	59,460		$	(18,817	)	$	1,122		$	2,722		$	488	$	452
Amortization of net (loss) gain	(14,917		)	(13,048		)	(2,069		)	(1,565		)	556		641
Settlements, mergers, sales, and closures	—			—			(737		)	—			—		—
Prior service cost (credit)	—			—			1,446			—			—		—
Amortization of prior service (cost) credit	1,573			1,573			(44		)	(44		)	—		—
Total change in other comprehensive income for year	$	46,116		$	(30,292	)	$	(282	)	$	1,113		$	1,044	$	1,093